Cyclonic separator with secondary vortex break

ABSTRACT

A cyclonic separator and methods of cyclonic separation which provide for a band pass separation of particles. That is, a cyclonic separator able to remove particles from an air stream that are greater than a predetermined minimum (which is greater than zero) while being smaller than a particular maximum. This band pass separation may be performed with the inclusion of a secondary vortex break on a cyclonic separator. Also discussed are cyclonic flow systems which provide for less deposition of aerosolized particles onto the cyclonic flow generator and related structures to improve likelihood of particles of interest being provided to an attached detector.

CROSS REFERENCE TO RELATED APPLICATION(S)

This Application claims the benefit of U.S. Provisional PatentApplication Ser. No. 60/560,122, filed Apr. 7, 2004, the entiredisclosure of which is herein incorporated by reference.

BACKGROUND

1. Field of the Invention

This disclosure relates to the field of cyclonic separators and the useof cyclonic flows to separate and isolate particles. In particular, thisdisclosure relates to the designs of cyclonic separator systems thatallow particles in a particular size band to be collected andtransferred to a separate flow as well as designs that lead to thereduction of particle buildup in the cyclonic flow generator and relatedcomponents.

2. Background of the Invention

The cyclonic separator is a well known general technology havingapplications from scientific research to today's bagless vacuumcleaners. The principle of operation is theoretically quite simple; thecyclonic separator uses rotational motion, and changes in rotationalmotion velocity to precipitate particles out of an air flow. In the caseof a vacuum cleaner, the cyclonic motion deposits particles of aparticular size or larger into a collection bin, then returns the airflow to the outside. In this way the dust and particles captured by thevacuum cleaner can be collected and disposed of.

Since the use of anthrax in the United States mail in October 2001,government organizations have become increasingly interested indetecting dangerous substances such as microorganisms, chemicals, orbiological warfare agents which could be unleashed on the United Statesto promote the agenda of a terrorist organization.

The transmission of agents is particularly of concern when used inaerosolized form where early detection may be difficult. Because largebuildings, subway systems, and the like utilize air circulation systemsin relatively self contained environments there is increasing concernthat the ventilation systems of these environments could be used in anattack to spread a dangerous warfare agent quickly and in a manner thatis difficult to detect. This scenario raises the level of interest inaerosolized contaminant detection.

The detection of aerosolized contaminants also commands great interestbecause it provides for a relatively easy and unobtrusive way to monitorobjects which might contain a warfare agent. No matter how careful aperson is, generally some particles of an agent are released into theatmosphere when that agent is being packed, transported, or loaded inpreparation of its being unleashed. The inability to completely containthe agent has led to a plethora of searching devices to detect warfareagents as well as other potentially aerosolized substances released fromthe surface of an item. Bomb- or illegal drug-sniffing dogs searchingfor such residue on luggage or packages are one such technology of thistype where the dog's nose can detect a minute amount of particlesaerosolized by the object's passing.

Another way to obtain samples of particulates that may be present in oron an object, is to use air to directly aerosolize the residue and carryit to a detector. Air may be purposefully flowed over objects ofinterest to dislodge and collect the minute particles without risk ofdamage or loss of privacy. U.S. patent application Ser. No. 10/449,612,the entire disclosure of which is herein incorporated by reference,describes embodiments of a system for obtaining aerosolized samples ofmaterials on or potentially included in mail.

One of the leading problems with aerosolized samples produced by thesemethods and even those produced through other actions, however, is thatthere is a large amount of air involved, even in a small application,and that air naturally includes a huge number of particles which are notof interest. Pollens, dust, pollutants, atmospheric microorganisms andother materials are always in the air to be sampled, thus makingdetection of the particles of interest more challenging.

Further, detectors sensitive to particular biological or chemical itemsof interest, generally have to process every particle they are providedwith. As the air will naturally include many particles which are not ofinterest, it is desirable to separate out as many of those particles aspossible before providing the air to the detector while still allowingparticles potentially of interest to be provided to the detector.Uninteresting particles can clog the detector over time, increasing theamount of maintenance required or decreasing the detector's life. It istherefore desirable to remove them from the air stream provided to thedetector.

Still further, to detect a multitude of chemical or biologicalmaterials, it may be necessary to have multiple different types ofdetectors. Each detector must process every particle in the air streamprovided to it to determine its relevance. Where each detector isprovided the air flow sequentially, detection may be too slow andcumbersome, especially where large air flow volumes need to bemonitored. Further, depending on the type of detector, if too manyuninteresting particles are present, detection of particles of interestcould become too attenuated.

Because of problems such as the above, most chemical and biologicalsystems utilize some form of particle separator to eliminate particleswhich are known to not be particles of interest. For example, if aparticular microorganism is being sought to be detected, particles whichare dramatically smaller or dramatically bigger than the microorganismdo not need to be tested. Traditionally, the particles have beenseparated using filters or cyclonic separators. Both these systems havea very noticeable problem, however, in that they cannot provideparticles in a size range that does not include one of the small orlarge size extremes. A cyclonic separator will trap all particles of thedesired size and larger, whereas a filter can only allow passage ofparticles of the desired size and smaller, trapping those particles of alarger size. These methods also have the problem that they requireregular checking to prevent clogging. In sum, this generally means thatparticles either above or below a particular size may be analyzed, butthere is no reasonable way to get particles in a particular range orband.

These methods also have trouble in applications where there are asubstantial number of particles present which are either larger orsmaller than the particles of interest and which cannot be wellseparated by the chosen methodology. In particular, if the desiredparticle is quite small and the system is operating in a dustyenvironment where there are a large number of uninteresting particles ofrelatively large size, a cyclonic separator will generally provide toomany particles to a detector, while a filter will rapidly become cloggedand fail.

Beyond the problems of inefficient separation, there is also the problemthat filter media and cyclonic separators will often stop particles ofinterest through deposition, either on the filter media (particularly ifit is getting clogged) or on the surface of the cyclonic separator orrelated structures during the cyclonic separation. Such trapping ofparticles of interest means that trace amounts which may need to bedetected, are instead confined to the separator and its relatedstructures.

SUMMARY

Because of these and other problems in the art, described herein is acyclonic separator which provides for a band pass separation ofparticles. That is, a cyclonic separator able to remove particles froman air stream that are greater than a predetermined minimum (which isgreater than zero) while being smaller than a particular maximum. In anembodiment, this band pass separation is performed with the inclusion ofa secondary vortex break on a cyclonic separator. Also disclosed hereinare cyclonic flow systems which provide for less deposition ofaerosolized particles onto the cyclonic flow generator and relatedstructures to improve likelihood of particles of interest being providedto an attached detector.

In an embodiment, the cyclonic separator comprises a primary separatorhaving an at-least-partially conical shape; a primary vortex breakhaving a generally conical shape, and a secondary vortex break, whereinsaid secondary vortex break is generally not conical but may becylindrical or of other volume in shape and has an output tube locatedon a side thereof. In an embodiment, the primary separator will beattached to the primary vortex break which is in turn attached to thesecondary vortex break.

In an embodiment there is described herein, a cyclonic separatorcomprising: a primary separator; a primary vortex break attached to saidcyclone; and a secondary vortex break, said secondary vortex breakattached to said primary vortex break and having an output tube attachedto a side thereof; wherein said cyclonic separator separates particlesin a particular band from other particles, said band having a minimumsize greater than zero and a maximum size; and wherein an air flowincluding a concentration of said particles in said band flows into saidoutput tube.

In an embodiment of the cyclonic separator, the separator furthercomprises a fan for pulling air and suspending particles into saidoutput tube.

In an embodiment of the cyclonic separator, the secondary vortex breakis not in the shape of an inverted cone, while the primary vortex breakor primary separator may be generally in the shape of an inverted cone.

In an embodiment of the cyclonic separator, the internal surface of atleast one of said cyclone and said primary vortex break is rough and mayhave surface roughness between about 16 and about 500 micro inches.

In an embodiment of the cyclonic separator, the minimum size of the bandis 0.85 micron while the maximum size is 12 microns. The concentrationof said particles may include a chemical or biological warfare agent.

In an embodiment of the cyclonic separator, the separator is arrangedvertically with said primary separator above said primary vortex breakwhich is in turn above said secondary vortex break so that separation ispartially accomplished by the force of gravity.

In an embodiment of the cyclonic separator, the secondary vortex breakis in the shape of a cylinder and output tube is arranged eitherradially or tangentially to said cylinder and may lead to a detector.

In another embodiment, there is described, a method for cyclonicseparation comprising: forming a first air flow, said first air flowbeing cyclonic; passing said air flow through a first choke point, saidfirst air flow splitting into a second air flow which flows internal tosaid first air flow and a third air flow which interacts with slowermoving air below said first choke point; having said third air flow andslower moving air pass through a second choke point and into a secondaryvortex break; drawing said air in said secondary vortex break outward;and collecting at least a portion of said air which is drawn outward.

In another embodiment of the method, the air which is drawn outwardincludes suspended particles which may include chemical or biologicalwarfare agents.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 provides a perspective view of an embodiment of a cyclonic flowseparator system including a secondary vortex break.

FIG. 2 provides a cutaway view of the embodiment of FIG. 1 showing thecyclonic air flow through the system.

FIG. 3 provides an exploded perspective view of an embodiment of asecondary vortex break.

DESCRIPTION OF PREFERRED EMBODIMENT(S)

FIGS. 1 and 2 provide for different views of an embodiment of a cyclonicseparator (100). The separator has three major components which in thisembodiment are arranged vertically to each other. This arrangementprovides a simple design for connection to related structures and otherequipment, but the vertical orientation of the cyclone is not necessaryto achieve proper performance. From the top to the bottom, a preferredembodiment includes a primary separator (101), a primary vortex break(107) and a secondary vortex break (111). While the preferred embodimentis arranged in this manner, the system can be rotated in space and stillfunction. This arrangement, however, provides for benefits as gravitywill help in the separation. Note that the sub-system comprised of theprimary separator (101) and the primary vortex break (107) may, in anembodiment, be replaced by a primary separator (101) with no primaryvortex break (107) being present. In an embodiment of the invention, theprimary separator (101) may alternatively be comprised of a cyclonicseparator of a type well known to those of ordinary skill in the art.Alternatively, in another embodiment, both the primary separator (101)and the vortex break (107) may be replaced by a cyclonic separator of atype well known in the art. Some of such cyclonic separators known inthe art are shown and described in U.S. Pat. No. 6,596,046, the entiredisclosure of which is herein incorporated by reference. In anotherembodiment, the entire cyclonic separator system (100) may be newlydesigned and built rather than incorporating designs alreadyconstructed. In a still further embodiment, a system of the prior artmay be built or modified to include the roughened surface discussedlater whether or not the primary vortex break (107) or secondary vortexbreak (111) is included.

The easiest way to understand the design of the system is to considerthe air flow as it moves through the system. Generally an air flow (201)will be directed into the primary separator (101) from the top. The flow(201) will enter the primary separator (101) through an inlet pipe orother structure. The primary separator (101) will generally be comprisedof a portion comprising an inverted cone. Generally, the primaryseparator (101) will be in the shape of a frustum of a cone, but neednot be. The primary separator (101) may also include a generallycylindrical portion (not shown) attached to the top thereof. The primaryseparator's (101) shape combined with the air flow inlet geometry willinduce the air flow (201) to spin creating a vortex or cyclone. Due tothe rotation of the air stream, particles suspended in the air streamexperience a centrifugal force causing them to move outward toward theinterior wall (105) of the primary separator (101). Larger particles areforced out first and as the rotation becomes tighter, smaller andsmaller particles are forced out. Particles reaching the interior wall(105) of the primary separator (101) are driven downward toward thefirst choke point (103) by the force of gravity and by the drag forcefrom the downward component of the air flow. As the flow (201)approaches the choke point (103), the rotation of the air flow willaccelerate leading to higher centrifugal forces causing smallerparticles to be forced from the flow.

Also, as the cyclonic flow (201) approaches the first choke point (103)it begins to turn in on itself and travel up through the center of thecyclonic flow (201), eventually to exit out the top of the primaryseparator, generally through an exhaust tube (not shown). This changefrom a downward cyclonic flow to an upward cyclonic flow is caused bythe relatively lower static pressure maintained in the center of thecyclonic flow (201) and in the exhaust tube, as well as by the shape ofthe primary separator (101). This flow reversal is generally completedinside the primary vortex break (107) into which the tip (202) of thecyclonic flow generally protrudes.

Particles that have been centrifuged out to the interior surface (105)of the primary separator (101) are moved down through the choke point bythe force of gravity and by the drag force from the downward componentof the air flow (201). Smaller particles are carried in the cyclonicflow (202) protruding into the primary vortex break (107). The larger ofthese smaller particles centrifuge out of the flow (202) inside theprimary vortex break (107) (as the rotation is at its highest in flow(202)) while the smallest particles remain suspended in the flow andtravel back up through the center of the cyclone to be exhausted. Thisaction upon the particles traveling through the cyclone (101) and intothe primary vortex break (107) acts as a high pass filter allowing ahigher percentage of particles above a particular size to pass into theprimary vortex break (107), being either centrifuged out of the air flow(202) or having been previously centrifuged out and pushed through thefirst choke point (103) by drag or gravity, while most of the particlesbelow that size are exhausted out the top of the cyclone (101) from theupward cyclonic flow.

Particles passing through the first choke point (103) that are not drawnup to be exhausted, enter the primary vortex break (107) wherecentrifugal forces in the cyclonic air flow (202) cause these particlesto be thrown out into the slower moving air (203) surrounding it. Inthis embodiment, the primary vortex break (107) is of a generallyconical shape. The portion of the cyclonic flow (202) protruding downinto the primary vortex break (107) maintains much of its slendertapered shape within the primary vortex break (107), much the same as atornado's shape tapers as it approaches the ground. The primary vortexbreak (107) takes advantage of this phenomenon to separate additionalparticles from the flow (202).

Regarding the larger particles separated from the cyclonic air flow(201) in the primary separator (101), the large diameter at the top ofthe primary vortex break allows particles traveling downward along thecyclone wall (105) to separate themselves from the cyclonic flow (202)as they pass through the first choke point (103). Particles suspended inthe flow (202) can also separate from that flow inside the primaryvortex break (107) since the rate of rotation of the cyclonic flow (202)continues to produce a centrifugal force on the particles suspendedtherein. In both these cases, the separation is accomplished because thewall of the primary vortex break (107) is at some distance away from thecyclonic flow (202) and therefore cannot provide the centripetal forcerequired to keep these particles in the flow (202).

Several outcomes may result for particles that separate from the flow(202) inside the primary vortex break (107). They may become suspendedin slower moving air (203) within the primary vortex break (107), whichis generally the case with the smaller particles separated in theprimary vortex break from flow (202), or impact the interior wall of theprimary vortex break (107) and travel downward toward the second chokepoint (109) in much the same way larger particles traveled in theprimary separator (101). Larger particles may also impact the interiorwall of the primary vortex break (107) and adhere to it. Preferably, thegeometry of the primary vortex break (107) is designed to suspend mostof the particles in the band of interest in the slower moving air (203).The resultant action within the primary vortex break (107), then, is aseparation of the larger of the small particles left in the cyclonic airflow (202) after passing through the first choke point (103). Thesmallest particles, therefore, remain in the air flow (202) while largerparticles are separated from the air flow (202). Both groups ofparticles will eventually enter the secondary vortex break (111) throughthe second choke point (109).

The secondary vortex break (111), as opposed to the primary vortex break(107), may be of any shape of sufficient dimensions to allow larger,uninteresting particles to settle out of the air flow (204) entering thesecondary vortex break (111) under the influence of gravity before theair flow (204) exits through the output tube (115). Generally, thisshape will be cylindrical but need not be and may be cubical,parallelepiped or any other volumetric shape. In a preferred embodiment,the secondary vortex break (111) will be generally cylindrical with adiameter in the range of 12 to 30 inches with a height between 10 and 20inches. The specific shape or dimension will generally be selected toprovide for uninteresting particles initially suspended in the air flow(204) and those passing into the secondary vortex break (111) notsuspended in the air flow (204) to settle under the influence of gravityto the bottom of the secondary vortex break (111).

In operation, as the air flow (203) passes from the primary vortex break(107) through the second choke point (109), it is comprised of a portionof the cyclonic flow (202) and a portion of the slower moving air (203),which is generally also rotating, and contains both interesting anduninteresting particles. Along with this, larger particles, in contactwith the interior wall of the primary vortex break (107), pass throughthe second choke point (109) under the influence of gravity and the dragforce from the downward component of the air flow (203); some of theseparticles are retained in the air flow as they pass through the chokepoint (109) and the rest are drawn down to the bottom of the secondaryvortex break (111) under the influence of gravity.

The air flow (204) enters the secondary vortex break as a thin stream ofhigh speed air spiraling in the same direction as the air flow (201) inthe primary separator (101). When this flow enters the larger diameterof the secondary vortex break (111), it is drawn to the perimeter of thesecondary vortex break by the output flow (205) which is maintained by afan (113), a blower, a pump, or a similar object. Therefore, the airflow (204) is made to travel for a duration of time in a more or lesshorizontal direction losing a significant amount of its cyclonic androtational action. During this time, the effect of gravity is utilizedto draw the heavier, uninteresting particles out of the flow and to thebottom of the secondary vortex break. Some of these particles, due totheir inertia may be centrifuged from flow (204) and impact the insidewall of the secondary vortex break, but by this action, they too areeffectively removed from the air stream (204). By adjusting the internaldiameter (or bottom area depending on shape) of the secondary vortexbreak (111), the duration in which this mechanism is employed can beincreased or decreased which will cause more or less large particles tobe removed from the air flow (204) before the air flow is directed intothe output tube (15) as flow (205). Namely, a larger diameter willgenerally result in smaller large particles separating while a smallerdiameter will allow these smaller large particles to remain in the flow.The particles settling to the bottom of the secondary vortex break (111)are generally held there by gravity and are not reintrained in the airflow (204) because the air flow in the bottom of the secondary vortexbreak is relatively stagnant, having very little motion with which todisturb the layer of particles that accumulates there.

Thus, the air flow (204) contains a high concentration of particles in aparticular band. The smaller particles (those below the band) have beenmostly exhausted to atmosphere in the upward flow of the flow (201) inthe primary separator (101) through the exhaust. The larger particles(those above the band) are separated from the air flow (204) and havebeen retained inside the secondary vortex break (111). Therefore, it canbe said that the initial air flow (201) has undergone a band passseparation of particles and that the resulting air flow (205) contains ahigher concentration of particles within a size band and a lowerconcentration of particles outside the band compared with the initialflow entering the system (201).

By locating the output tube (115) on the side of the secondary vortexbreak (111) instead of on the base and at a sufficient height andlocation about the perimeter of the secondary vortex break (111) and byselecting the dimensions of the secondary vortex break (111), the outputtube (115) can capture the desired band of interesting particles carriedin the air flow (204), or even a portion of the band carried by the airflow (204). The output flow (205) then transports these particlesleaving the secondary vortex break (111) on a path to a detector orother processing equipment. In order to capture particles in air flow(204), an embodiment of the secondary vortex break (111) will preferablyhave the output tube (115) located anywhere from 1 to 12 inchesvertically downward from the secondary choke point (109) depending onthe band of particles desired and the size of the secondary vortex break(111). The specific characterization (e.g. particle size) of the bandcarried in air flow (205) can be adjusted, as would be understood by oneskilled in the art, by altering the geometry of the primary separator(101), primary vortex break (107), and secondary vortex break (111) andthe positioning of the outlet tube (115), as well as by altering flowrates and velocities of air flows (201) and (205).

Additionally, the secondary vortex break (111) and its output pipe (115)provide another unique function in that their geometry is capable oftransforming a flow having relatively high cyclonic action (204) intoone having relatively low cyclonic action (205). An air flow havingrelatively high cyclonic action cannot travel through a pipe or tubewithout losing a significant number of its suspended particles to thewall of the tube (115). This loss is caused by the high-speed rotationof the air flow within the tube (115) centrifuging the particles out tothe interior surface of the tube (115) where they can adhere to the wallof the tube (115). If a tube (115) were connected directly to the output(109) of the primary vortex break (107) or even to the bottom (103) ofthe primary separator (101) body itself in an attempt to carry thehigh-pass particles to a detector, due to the continuing cyclonic motionof the air flow a significant number of particles in the band, as wellas larger particles still suspended in the flow, would be centrifugedout to the wall of that tube (115) resulting in a significant reductionin the number of interesting particles reaching the detector.

The accumulated particles can also result in clogging of the tube (115)and decreased efficiency. By utilizing the geometry of the secondaryvortex break (111) and its output tube (115), and connecting thesecondary vortex break (111) to the output of the primary vortex break(109) or even to the output of the primary separator (101) itself, thecyclonic flow (201) traveling down the primary separator (101) is causedto change direction in the second vortex break (111) and exit more orless perpendicularly to the centerline of the cyclonic separator (100).The resultant air flow (205) comprises a relatively low cyclonic flowand therefore, can transport its suspended particles to a detector withsignificantly less loss to the wall of the tube (115) as compared withair flow that enters a tube (115) with a cyclonic or other rotationalmotion.

The output tube (115) of the secondary vortex break (111) may bearranged tangentially, radially, or anywhere in between relative to theside wall of the secondary vortex break (111), however, it is preferredthat it be arranged generally radially thereto and located at the pointwhere the particles of the desired size band begin to interact with theinside surface of the secondary vortex break (111). This radialarrangement generally provides for easier construction and improvedsuspended particle capture.

FIG. 3 shows an embodiment of a secondary vortex break (111) that may beused in a cyclonic separator as discussed above. This secondary vortexbreak (111) is cylindrical and may be attached to the primary vortexbreak (107) by any means known to one of ordinary skill in the artincluding, but not limited to, custom fittings, screw threads, welding,or unitary construction. This embodiment is comprised of a generallycylindrical main body (401) with an upper open surface and a closedbase, the upper surface may have a lip (403) to facilitate connection tothe lid (411), or the main body (401) may be connected to the lid (411)by some other method. In this embodiment, the upper surface or lip (403)is attached by a plurality of screws (405) which interact with aplurality of holes (407) on the top (411). Alternatively, the screws(405) may be replaced with pins or other types of connectors to hold thetop (411) to the main body (401). The top (411) serves to cover the topof the main body (401) forming a generally enclosed cylinder. The mainbody (401) is, however, removable from the lid (411) to allowaccumulated particles in the main body (large particles) to be disposedof. At or around the center of the top (411), there is a hole (413)which will serve to connect to the output of the primary vortex break(107). For this reason, the hole (413) will generally be sized andshaped to be of generally the same size as the choke point (109).

The band pass nature of the cyclonic separator (100) is particularlybeneficial when the particulates of interest for analysis are known tobe of a particular general size. Without the use of a secondary vortexbreak (111), larger, uninteresting particles are not removed and are fedinto the output tube (115) along with those in the band of interest.This means that the uninteresting particles would either be carriedthrough to the detector which leads to slower processing and decreaseddetector life or, along with some particles of interest, be deposited onthe inside of the output pipe (115) which reduces the system's detectioncapability, decreases air flow to the detector, and increases the needfor cleaning.

Even though one's best judgement and extreme care are utilized in thedesign and manufacture of the cyclonic separator (100) and itscomponents, particles in the desired band can still be forced out of theair flow (201) and deposited on the inside surface of the primaryseparator (101) or on the inside surface of the primary vortex break(107). In these cases, particles of interest may be permanentlyprevented from reaching the detector in air flow (205). This can beespecially problematic where very few particles of interest may bepresent in the air flow (201). While the system described above canconcentrate particles into the band, some particles in the band maystill be lost.

In an embodiment, this deposition can be reduced through the interiordesign of the primary separator (101), the primary vortex break (107),and even the secondary vortex break (111). In particular, if theinterior surfaces of some or all of these items is made with a roughsurface, the deposition of the particles of interest can be reduced,allowing more of these particles to pass into the next section of thecyclonic separator (100). This modification can also be used to reducedeposition in traditional cyclonic separators; however, it can beparticularly beneficial in a band pass embodiment, such as thatdescribed above, as fewer particles of interest adhere to the wall.

In an embodiment in which the cyclonic separator (100) is used toimprove the collection of particles in the 0.85 to 12 micron range(which can be useful for detection of respirable chemical or biologicalwarfare agents), a surface roughness of 16 to 500 micro inches willgenerally be preferred. Such a roughness can lead to an improvement offrom 30% to 400% over smooth surfaces depending on the particle size andvarious other factors. In testing, the rough surface has proven to bebetter than a smooth surface because the rough surface generally createssurface effect flows in the air flow (201) near the inner surface (105)of the cyclone (101). These surface effect flows increase a particle'smomentum which helps prevent it from adhering to the surface (105) whenit comes into contact with it. These flows, therefore, improve thechance of particles of interest being passed into the next component ofthe cyclonic separator (100). For a particle in the size band ofinterest, it is then more likely that the particle will travel throughthe system (100) and end up in air flow (204) and pass into the flow(205) and to the detector.

As would be understood by one of ordinary skill in the art, theparticular size values of particles which pass through the high passfilter of the cyclone (101) and primary vortex break (107), and passthrough the low pass filter of the secondary vortex break (111) arebased on the relative diameters, sizes, and shapes selected for each ofthe components of the cyclonic separator (100), as well as thepositioning of the output tube (115) relative to the base and diameterof the secondary vortex break (111). Further, previously discussedranges are merely exemplary of certain ranges and are by no meansintended to be exhaustive.

It should further be recognized that variations of this cyclonicseparator system (100) can be combined together in parallel or series toprovide multiple band pass ranges (having wider or narrower bands ineach separator, as need be) to different detectors. For example, severalcyclonic separators (100) could be designed to produce different bandpass ranges in their output flows (205). These cyclones could be gangedtogether in parallel as a unit to sample particles from a common airstream but deliver the particles in different size ranges to differentdetectors.

Cyclones could also be connected in series by directing all or a portionof the output flow (205) into a cyclone (101) or into the primary vortexbreak (107) of a second cyclonic separator (100). Another method forconnecting cyclones in series to provide multiple band pass ranges woulddirect the exhaust flow leaving the top of a cyclonic separator (101)into the intake flow (201) of a second cyclonic separator (100). Inanother example, the deposition in the secondary vortex break (111)above may be sent into a primary separator (101), or primary vortexbreak (107) of another cyclonic separator (100). These combined systemsmay then connect to additional cyclonic separators (100) as required,each providing a particular band pass separation from the initial air.Each of these cyclonic separators (100) may also have additional airflow (201) provided to them to provide improved operation and similarband pass separation to that above, but with a different band. The abovedescribed cyclonic separators (100) may also be used in conjunction withthose of the prior art to provide both band pass and low or high passseparation together.

While the invention has been disclosed in connection with certainpreferred embodiments, this should not be taken as a limitation to allof the provided details. Modifications and variations of the describedembodiments may be made without departing from the spirit and scope ofthe invention, and other embodiments should be understood to beencompassed in the present disclosure as would be understood by those ofordinary skill in the art.

1. A cyclonic separator comprising: a primary separator; a primaryvortex break attached to said primary separator at a first choke point;and a secondary vortex break, said secondary vortex break attached tosaid primary vortex break at a second choke point and having an outputtube attached to a side thereof; wherein said cyclonic separatorseparates particles in a particular band from other particles, said bandhaving a minimum size greater than zero and a maximum size; and whereinan air flow including a concentration of said particles in said bandflows into said output tube.
 2. The separator of claim 1 furthercomprising a fan for pulling air and suspending particles into saidoutput tube.
 3. The separator of claim 1 wherein said secondary vortexbreak is not in the shape of an inverted cone.
 4. The separator of claim1 wherein said primary vortex break is generally in the shape of aninverted cone.
 5. The separator of claim 1 wherein said primaryseparator is generally in the shape of an inverted cone.
 6. Theseparator of claim 1 wherein the internal surface of said primaryseparator or said primary vortex break is rough.
 7. The separator ofclaim 6 wherein said surface roughness is between about 16 and about 500micro inches.
 8. The separator of claim 1 wherein said minimum size is0.85 micron.
 9. The separator of claim 1 wherein said maximum size is 12microns.
 10. The separator of claim 1 wherein said separator is arrangedvertically with said primary separator above said primary vortex breakwhich is in turn above said secondary vortex break.
 11. The separator ofclaim 10 wherein said separation is partially accomplished by the forceof gravity.
 12. The separator of claim 1 wherein said secondary vortexbreak is in the shape of a cylinder.
 13. The separator of claim 12wherein said output tube is arranged radially to said cylinder.
 14. Theseparator of claim 12 wherein said output tube is arranged tangentiallyto said cylinder.
 15. The separator of claim 1 wherein said output tubeleads to a detector.
 16. The separator of claim 1 wherein saidconcentration of said particles includes a chemical or biologicalwarfare agent.
 17. A method for cyclonic separation comprising: forminga first air flow, said first air flow being cyclonic; passing said airflow through a first choke point, said first air flow splitting into asecond air flow which flows internal to said first air flow and a thirdair flow which interacts with slower moving air below said first chokepoint; having said third air flow and slower moving air pass through asecond choke point and into a secondary vortex break where said thirdair flow interacts with slower moving air below said second choke point;drawing said air in said secondary vortex break outward; and collectingat least a portion of said air which is drawn outward.
 18. The method ofclaim 15 wherein said air which is drawn outward includes suspendedparticles.
 19. The method of claim 16 wherein said suspended particlesinclude chemical or biological warfare agents.